Method of and apparatus for disposing of sewage waste



Feb. 28, 1939. w. A/DUNDAS ET AL 2,148,447.

METHOD OF AND APPARATUS FOR msPos'Ine OF SEIVWAGEWASTE Filed Aug. 26, 1935 8 Sheets-Sheet l W. A. DUNDAS El ALv Feb. 28, 1939.

METHOD OF AND APPARATUS FOR DISPOSING OF SEWAGE WASTE Filed Aug. 26, 1933 8 Sheets-Sheet 2 Feb. 23, 1939. w. A. DUNDAS 5T AL METHOD OF AND APPARATUS FOR DISPOSING OF SEWAGE WASTE Filed Aug. 26, 1933 8 Sheets-Sheet 3 fiuc jdbr-s Dwzdas A \Wmm wwm www 46% Feb. 28; 1939. w. A. DUNDAS ET AL 2,148,447

METHOD OF AND APPARATUS FOR DISPOSING 0F SEWAGE WASTE Filed Aug. 26; 1935 8Sheets-Sheet 4 Feb. 28, 1939.

w. DUNDAS ET AL METHOD OF AND APPARATUS FOR DISPOSING OF SEWAGE WASTE Filed Aug. 26, 1955 8 Sheets-Sheet 5 Feb. 28, 1939. 2,148,447

METHOD OF AND APPARATUS FOR DISPOSING 0F SEWAGE" WASTE w. A. DUNDAS ET AL Filed Aug. 26, 1933 8 Sheets-Sheet 6 Quh,

Nmm Nah mama Feb. 28, 1939. w. A. DUNDAS El AL METHOD OF AND APPARATUS FOR DISPOSING OF SEWAGE WASTE Filed Aug. 26 1933 8 Sheets-She et 7 a am mmw MQM Feb. 28, 1939. w. A. DUNDAS ET AL 2,148,447

METHOD OF AND APPARATUS FOR DISPOSING OF SEWAGE WASTE Filed Aug. '26, 1955 1 8 She-ts-Sheefc 8 sewage disposal involves the separation of the' water from the more or less solid ingredients and Patented Feb. 28, 1939 UNITED STATES METHOD OF AND APPARATUS -FOR DIS POSING OF SEWAGE WASTE William A. Dundas, Wiunetka, and Philip Harrington, Wilmette, 111.

Application August 26, 1933, Serial No. 686,926 59 Claims. (Cl. 110-15) 'I'hisinvention relates to improvements in "methods of and apparatusfor the disposal of sewage wastes and its purpose is to provide means for accomplishing this object more efliciently and economically than it has heretofore been done by the methods commonly in use. Although particularly adapted for the treatment of sewage waste, the invention may be employed in the disposal .of garbage, rubbish and other municipal wastes or other wastes and the like, or mixtures thereof. Sewage consists of a mixture of water, minerals and other inert inorganic materials and organic materials either in suspension or solution and garbage and rubbish are similar in that they usually include mixtures of organic and inorganic material and water. The problem of the disposition of these solid ingredients in an economical manner without creating a nuisance in the region-where the operation is carried on.

' All presently known methods for the purification j and treatment of sewage and the disposal of the waste products of such methods consist of separating more or less perfectly the water from the other materials contained in the sewage after which the water is ordinarily run of! to open streams or bodies of water and the other separated materials are disposed of in various ways. These waste materials, commonly known as sludge, screenings and grit, consist of the inorganic androrganic ingredients 'of the sewage together with some water which has not been separated by the initial treatment. The organic materials consist mainly of vegetable and animal matter, including a large percentage of volatile and combustible material, while the inorganic materials are largely in the form of inert min erals. These more or less solid ingredients of the sewage are ordinarily disposed:=of either by mechanical dewatering and processing intofer tilizer for which the market is limited, or by digestion followed by partial dewatering carried on in drying beds and again followed by dumping .on waste land, or by partial digestion and evaporation in lagoons, or by dumping the material at sea' or in open rivers and lakes. Where the sewage wastes are disposed of in lagoons or on drying beds, the disposal is usually uncertain,

seasonal and intermittent, being dependent upon weather conditions and requiring the storage of the sewage waste for long periods before it can be' spread out on the drying beds for the evaporaflon of the water carried therein.v In addition, these methods of disposal of the organic and g is preferably such that no properties or contents found in all sewage waste materials, and which are found in the waste materials in sufficient quantity to make them practically capable of supporting combustion without the addition of any appreciable quantities of supplementary fuel when incinerated by the methods described in the following specification.

The principal object of the present invention is to provide an improved method of and appa-' ratus for disposing of sewage waste according to which the process of disposal is carried on economically and continuously with the reduction of the solid matter to an inert form .of small volume and with the complete destruction of all offensive odors. A further object of the invention is to provide an improved process of sewage waste disposal according to which the waste materials are treated continuously, being subjected to a dewatering step and then being disposed of by incineration, leaving only the inert ash, and the gases of "combustion, which are preferably utilized in drying the materials prior to the incineration thereof. A further object of the invention is to provide a method of sewage waste disposal in which the water content of the waste material is reduced mechanically and thermally preliminary to pulverizing and the gases of combustion are carried to points where their heat is utilized n effecting the drying of the-' waste materials in an early stage of the process. In this invention, the arrangement gases of combustion or steam produced by thermal dewatering are permitted to escape to the atmosphere without passing through a high temperature zone forcomplete destruction of possible odors. A further feature of the invention is .to provide an improved method of sewage waste I incineration of. the major portion of the solid ingredients of the sewage and the maintenanceof the combustion by these ingredients alone or by the mixture therewith oi comparatively small quantities of fuel such as coal, oil or gas. Still another object of the invention is to provide improved forms of apparatus for use in carrying on various steps of the improved pm of the present invention. Other objects relate to various features of construction and at flag disposal involving they heating the solid ingredients I of the waste in preparation for the burning of these ingredients in a closed chamber from which apparatus and to details of the method which will appear .more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which several embodiments of the improved method of the present invention are illustrated in connection with various forms of apparatus which may be employed in practicing the method. In the drawings,

Fig. 1 shows a somewhat diagrammatic view of the principal parts of the apparatus and the connections therefor which may preferably be employed in practicing the improved method of the present invention;

Fig. 2 is a somewhat diagrammatic representation of the electrical connections of the various motors which are shown in Fig. 1 for driving difierent parts of the apparatus whereby an interlocking system is provided for controlling the operation of the motors;

Fig. 2 is a continuation of the diagrammatic showing of Fig. 2, illustrating the electrical connections to other motors included in the sludge disposal system illustrated in Fig. 1;

Fig. 3 is an enlarged diagrammatic representation 201 certain circuit breakers illustrated in Fi Fig. 4 represents an enlargement of a portion of Fig. 2, illustrating somewhat in detail the parts of the reset relay;

Fig. 5 is an enlarged vertical section through a portion of the hot gas conduit leading to the drying tower shown in Fig. 1, illustrating the means for controlling the closing of a damper therein;

Fig. 6 is a diagrammatic view showing the apparatus used for practicing the invention according to another modification;

Fig. 7 is a diagrammatic view showing still another modification of the apparatus and method of the present invention;

Fig. 8 is a diagrammatic view showing still another modification of the invention;

Fig. 9 is a diagrammatic view showing the means for practicing the present invention with the use of av rotary drying kiln for heating and $271118 the sludge in the first stage of the opera- Fig. loisanenlargedsectiontaken ontheline ll-Il of Fig. 9.

The apparatus to be usedin the practice of the present invention is, in general, of standard make or design but where special forms of apparatus are preferably to be employed, such forms are illustrated and described in greater detail than are those parts which form the principal elements in the somewhat diagrammatic illustrations of the drawings. Referring to the form of the invention illustrated in Fig. 1', the sewage waste material II, which may contain from one to twenty percent by weight of solid matter, after mixing with a suitable conditioner or coagulant such as ferric chloride, is introduced into a dewatering apparatus, for example, into the tank of a rotary filter ll of the vacuum'type which comprises a cloth covered cylindrical drum ll", partially submergedin the material ll contained within the tank and moimted for rotation about a horizontal axis. The space within 'the cylinder'll'is di-' vided into chambers by division walls I I and a connection is made with suction pipes I! so that a partial vacuum may be maintained in each of the chambers ll of the drum durin'gits rotation. This vacuum connection is ordinarily made through the hollow shaft of the drum but is illustrated diagrammatically as being established by suction pipes leading to the separate chambers when the chambers are in certain positions with respect to the tank in which the sewage waste is contained. As the drum rotates through the tank, the suction causes the solid material of the sewage waste to be separated from the water and deposited upon the cylindrical surface of the drum and when one of the chambers is carried above the surface of the fiuid by the rotation of the drum. in the direction of the arrow i3, the suction serves to draw the water out of the waste material while at the same time causing it to adhere to the drum until it reaches a point where it engages an inclined scraper blade i l. At this point, the chamber located within that portion of the cylindrical space of the drum establishes a fluid-tight connection with the air pipe l5 which creates a pressure in the chamber and assists the blade I4 in removing the solid waste material I6 which then falls by gravity into a hopper l1. If desired, other forms of dewatering apparatus, such as presses, centrifuges and traveling screens, may be employed in place of the rotary vacuum filter. A belt conveyor 2| is also arranged to discharge into the hopper I! a quantity of dried or partially dried sewage waste 22 from a succeeding stage of the process. From the bottom of this hopper, the mixture of wet and dry waste material is moved through a conveyor tube l8 having mounted therein a screw conveyor l8"- driven by a motor III. The conveyor tube discharges the material into a drying tower which is mounted in a vertical position. The incoming mixture of wet material l8 and dried material 22 is ground up by suitable devices such as a pair of rotary chopping devices 23, comprising rotary drums having radiating blades adapted to mesh with each other during the rotation of the drums as these drums are driven by power means, not. shown. The waste materials are thus thoroughly mixed and more or less finely divided and they then drop by gravity through the tower 20 where they mingle with a stream of hot air introduced through the conduit 24 and heated to a high temperature, for example, 1500 degrees F., by heat developed in the incinerating stage of the process, as hereinafter set.

forth. The flow of heated air through this conduit 24 may be controlled by a valve 25. The

-mixture of the wet material with the hot air results in an exchange of heat to the colder material and a corresponding drop in temperature of the air which will be cooled to a point of safety for introduction into the mill, for example, about 800 or 900 degrees F.

The waste material then passes by gravity from the bottom of the tower 20 to a pulverizing and drying mill 21 comprising a main casing 21- and an auxiliary casing 2l having a horizontal shaft 22 journaled in the walls thereof. A plurality of disks 2! are secured on the shaft 28 within the main casing 21' and a series of beater arms 30 are pivotally mounted on thm disks so that they fly out by centrifugal force and engage the incoming waste material with the result that it is pulverized-to a finely divided state. The auxiliary casing 21'', which is in direct communication with the main casing 21-, contains a' fan or impeller II which is fixed upon'the shaft 28and "which serves to maintain a circulation of the mixture of air, solid matter and steam produced by evaporation through the casing Hand also to discharge the finely divided material, air and steam upwardly through a conduit 32 as the shaft 20 is rotated by the electric motor 26. This concentral outlet at its lower end or apex. The air andvapor contained in the mixture received through the conduit 35 is drawn upwardly through the division wall 36'' and through a conduit 31 by a fan 38 which is driven by an electric motor 33 and which discharges the mixture of air and vapor through a conduit 40. The solid mat-' ter separated in the centrifugal separator 36 drops by gravity through the central opening of the lower cone-shaped wall 36' with the result that a portion of it passes through the branch conduit 4| to the belt conveyor 2i previously described which serves to convey this dried or partially dried material to the hopper I1. The remaining portio of the material dropping from the separato 36 passes through another conduit 42 to th next stage of the process.

The conduit 42 discharges into'the uppe end of another drying tower 43 into which hot air is introduced through a conduit 44 communicating with its upper end. As the waste material drops through the tower 43, it mingles with and is further dried by the hot air introduced by the pipe 44 and it then discharges into a second rotarypulverizing mill 4l which is similar to the mill 21 previously described, comprising a main casing 41 and an auxiliary casing 4'! in which are mounted parts having the same form and bearing the same reference numbers as those described in connection with the mill 21. This mill "may also be provided with a branch conduit 45 leading from a hopper 46 which may contain lump coal, for example, adapted to be pulverized in the mill and mingled with the waste material for the purpose of assisting in maintaining com bustion in the subsequent incinerating stage of charges the material, under the pressure of the f'an, into the upper end of a closed incinerating furnace 52. A conduit-53 leads through the top wall of the furnace and discharges adjacent the flared mouth of the conduit 50 for the purpose of supplying heated air for maintaining combustion of the powdered material and another conduit 54 is led through the side wall of the furnace to discharge at a point beneath the mouth 50' of the conduit 50 for maintainingcome bustion in the lower part of the furnace chamber. The pulverized and dried waste material is thus burned while in suspension in the furnace chamher and the ash drops onto the lower wall 52" of the furnace which is constructed in the form of aniinverted cone and which has an outlet 52 through which the inert fish is discharged by gravity to cars or pipes for final disposal.

The hot gases of combustion are, discharged from the topof the furnace chamber through aconduit 55 which has a branch 56 leading tothe atmosphere andcont'rolled by a valve 5'! which may beipartiallyor wholly closed, depending upon the conditions of, operaflon. Ordinarily, tliehotgasesofcombustionortheprincipalportion thereof pass, from the conduit 5! through a branch conduit 58* which leads to a preheater l3.

s This preheater has mounted therein a hollow coil 59 which is connected by a conduit 60 with a fan 6| driven by a motor 82 and adapted to draw hot air through a conduit 63 from the chamber 84 formed within the hollow wall of the furnace 52. This chamber 64 has an inlet 64 located. opposite the conduit 63 so that. when the fan 6| is in operation, air is drawn from the atmosphere through the wall of the furnace and is thereby heated before it reaches the fan 6|. This air is then carried upwardly through the conduit 60 and is further heated by the hot gases of combustion which circulate around the coil 59 through the heater 58. Hot air from-the coil 59 is then discharged through the previously described conduit 24 which leads to the drying tower 20. A cold airconduit 65 is preferably arranged to comm cate with the conduit 24 adjacent the drying tower 20 and a damper 65' may be provided in this cold air conduit for regulating the flow of cold air in order to maintain a substantially uniform temperature of the heated air which reaches the cooling tower through the conduit 24. If desired; the damper 51 in the waste gas conduit and the damper 65 in the cold air conduit may beelectrically controlled by means responsive to temperature' conditions.

In addition to effecting the heating of the contents of the coil 59 within the preheater 58, the hot gases of combustion serve also to operate.a second preheater and for this purpose they are carried upwardly through a conduit 68 from the preheater 58 to a superimposed preheater 88 having mounted therein a coil 63. The coil 63 is connected at one end to the previously described conduit 44 to which the branch conduits 53 and 54 are connected and at its other end the coil 63 is connected to the previously'described conduit 40 so that this preheater serves to heat the air which is supplied to the furnace chamber and also the air which is supplied to the upper end of the drying tower 43. From theupper end of the chamber of the preheater 6,8, the gases of. combustion are carried upwardly through aconw duit l0, and introduced into. one or moresepa'rators II which serve to separate from the gases the finely divided ash contained therein, allowing this ash to drop through the bottom of the separator as shown at 1| while the gases are discharged from the upper end of the separator to the at? mosphere, as shown at 11'. A motor 12 is preferably employed for driving a fan 13 connected in the conduit 10 for inducing a draft from the pre-heater chamber upwardly .to the separator I I.

In Figs. 2 and 2" there is illustrated, somewhat diagrammatically, one arrangement of electrical circuit connections and electrical apparatus which may, be, employed for. providing an .inters.v

results arising from the accidental stoppa e of any motor in the illustrated system; For example, if the first mill 21 he accidentally shut down by reason of the stoppage of its motor 23, the electric motor I! which drivesthe conveyor I3 is automatically shut down in order to prevent the feeding of wet sludge into the mill; At the same time that this occurs, .the'damper'2l is automatically closed in order to prevent the passage of highly heated gases into the drying tower 20 and into the mill 21. Also, if any of the preheater fans or induced draft fans are stopped by reason of the stoppage of their driving motors, the driving motors of the mills operating in conjunction with those fans and the driving motors of all conveyors and exhaust fans connected with those mills are automatically stopped in order to prevent wet sludge from entering and clogging the mills while the preheater and induced draft fans are out of service.

The electrical system illustrated in Figs. 2 and 2 by which the foregoing results and other advantages are obtained comprises three electrical conductors 80, 80 and 80 leading from a source of three-phase current supply, the system being herein illustrated in connection with a three-phase alternating current system although it will be understood that the improvements of the present invention may be practiced with a two-phase alternating current system or with a direct current system, if desired. These conductors supply current'to two series of buses including a first series 8|, 8 I and M and a second series 82!, 82 and 82. The series of buses 8|. 8I and III supply current to the motors for driving the pre-heater fans, the induced draft fans and the second stage mill, while the buses 82*,82 and 82 supply current to the motors for driving the conveyor, the first mill and the exhauster. Referring first to the electrical connections to the motor 28 by-which'the second stage mill is operated, the buses 8|, BI and 8i are connected to the motor through three conductors 83, 83 and 83, respectively, which in turn are connected through the contactors 84.0f a motor starter 85 with the conductors 85, 80 and 88 having connections with the terminals of the motor 25. The motor starter 85 has its contactors 84 connected {or operation by a rod 81 which is actuated by a series of mechanical connections leading to a closing coil 88. This closing coil is connected across one phase of the circuit through overload relay coils 30, contacts 00, conductors 3I, momentary contacting push button 32 and conductor 03. Upon momentarily closing the push button 32, the closing coil 88 is energized and the rod 81 isoperated to close the contactors 84 and thereby complete the circuit from the buses 8|, 3| and 8I of the motor 25. The circuit thus 'established is maintained by reason of the fact that a normally closed push button contact 33 establishes a connection from one of the conductors 3| to the conductor 35 to which the conductor 31 is connected, thus maintaining a circuit through the coil 33 and holding the contactors 04 in their closed positions. In case of an overload on the motor 20*, the excess currentpasses through each of the conductors 33' and 38 with the result that the coils of the. overload relays 33 operate the contacts" to open them. and thereby deenergize the coil 83, with the result that the contactors 34 are automatically moved to their open positions, thereby opening the motor circuit. In asi'milar way and by similar connections and parts bearing the same reference numerals, motor starters 85, 85 and 35 are employed for establishing connections to and controlling the starting of the electric motors I2, 33 and 02, respectively, which are employed for driving the induced draft fans, the second preheater fan and the first preheater fan, respectively.

when the system is running under normal conditions, the supply circuit is maintained in closed position by a circuit breaker I which is illustrated diagramatically in Fig. 2 and shown in somewhat greater detail in Fig. 3. This circuit breaker comprises three carbon and copper contacts IOI which are carried by a common bar I02 having an operating lever I03 provided with a handle I04. The lever I03 is mounted on a shaft I which is adapted to pivot aboutits axis when the contacts IOI are moved toward and from their closed positions. The contacts IOI are adapted to be held in closed position by a coil I06 which, when its circuit is energized, causes a latch member I01 to engage parts associated with the shaft I05 to hold it from turning. When the coil I06 is deenergized, the latch member I01 moves downwardly under the influence of a weight I08, thereby allowing the lever I03 with its contact member IOI to move to open position. The shaft I05 has mechanical connections with an arm I09 which operates the auxiliary contacts I I0 located in an auxiliary circuit, hereinafter described. The coil I06 is connected across one phase of the supply circuit by means of a conductor I II connected to another conductor II2 having connection with one of the supply conductors 80 and another conductor II3 leading through a resistor H4 and the conductor II5 which is connected to another supply conductor 80. When this circuit is established, the coil I08 is energized and the circuit breaker is maintained in its closed position. Y

The circuit breaker I00 is interlocked with the circuits of the motor starters 85, 85 85' and 85 through a reset relay I20, the connections and mechanical features of which are illustrated somewhat diagrammaticallyin Fig. 4 in addition to the general illustration of Fig. 2. The reset relay comprises a shaft I2I having mounted upon it four contact members I22, I23, I24 and I25 which are adapted in certain positions to establish connections between opposed pairs of stationary contacts I25, I21, I28 and I28, respectively. Two of the contact members I24 and I25 are connected at right angles to the other two contact members I22 and I23 so that when two of the pairs of stationary contact members are connected by the movable contact members, the other two pairs of contact members are disconnected. The shaft I2I is provided with a relatively-fixed cam I30 having a notch I33 adapted to be engaged by the plunger I3I of a magnetizable coil I32 which, when it is energized, withdraws the plunger I3I to permit .the cam and the shaft I2l to be rotated. When the coil I32 is deenergized, the plunger I3I is permitted to fall by gravity into the notch I30,

A thereby holding the cam and shaft I2I against rotation, assuming thatthe cam I33 has previously been rotated to a position where the notch I30 is in alignment with .the plunger. The turning of the cam for this purpose is effected by a handle I33 having a connection with a coil spring I34 which operates automatically to return the shaft III and the contact bars to the position shown in- Pig. 4 when the-coil I32 is energized to elevate the plunger I3I.

. when any one of the motors 269, 38, 02 or 12 is thrown out of operation by any one or more of the circuit breakers heretofore described, the coil I33 of the circuit breaker I00 is automatically short-circuited through electrical connections which are made with contacts adapted to'be controlled by the deenergizing of the coils 38 when the circuit of the associated motor is opened' and, to eliminate the short circuit thus established and permitthe circuit breaker I to be again closed, the reset relay I20 is operated. Before describing the operation of the reset relay reference will be made to the circuitsby which the coil I06 of the circuit breaker I00 is short-circuited. This short-circuiting may be efiected by any one of a series of contacts I35, I35, I35 and I35 which are associated with the coils 68 of the motor starters 85, 85, 65 and 85, respectively. These contacts I35 are connected in parallel by conductors I38 and I31 and the conductors I36 and I31 are in turn connected on opposite sides of the coil I06 to a conductor I38 leading to the clam ductors III and H2, and another conductor I38 which leads to one of r the stationary contacts I26 of the reset relay. The other stationary contact I26 is connected through a conductor I40 with the conductor I I3 which connects the coil I06 with the resistor II4 previously described. When the reset relay is in the position shown in Fig. 4, with the contact member I22 establishing a connection between the stationary contacts I26, the

closing of the contacts I35 01' the motor starter 85,

by the deenergizing of the coil 88 associated with automatically opened. Assuming that the contact members IOI are in open position, which is the position they would have when the sludge disposal system is not in operation, the first step to be taken to eliminate the short circuit and permit the closing of the circuit breaker, I00 is to turn the handle I33 of the reset relay, thereby rotating the shaft I2I through ninety degrees from the position shown in Fig.4 until the contact member I22 breaks the connection between the stationary contacts I26. At the same time that the contact member I22 passes out of connection with the stationary contacts I 26, the contact member I23 becomes disengaged from thecontacts I21 and the other two movable contacts I24 and I25 establish connections between the other two pairs of stationary contacts'I28 and I 23, respectively. With the opening of the connection between the contacts I 26 bythe rotation of the handle I33, the short circuit of the 'coil I06 is eliminated so that when the contacts IOI are closed by manipulation" of the handle I04,

the coil I06 may be energized and then operates the latch I01 to hold the circuit breaker in its closed position.

To prevent the reset relay I20 from returning automatically to its normal position after it has just been operated after the manner described in the preceding paragraph, the movable contacts I24 and I25 and their associated stationary contacts I28 and I28, respectively, with their connected circuits, are provided. The upper con-.

tact member I28 is connected by a conductor I4I with the conductor II previously described and the lower contact member I28 is connected by a conductor I42 with a resistor I43 which is in turn connected through a conductor I44 with the conductor I38. The conductor I44 is also connected through a conductor I46 with one terminal of the coil I32. The other terminal of the coil I32 is connected through a conductor I41 with the lower stationary contact I28. The upper stationary contact member I29 is connected through a conductor I48 with the conductor I38 previously described. As long as any one of the auxiliary contacts I35, I35, I35 or I35 is closed, the current will flow from the line conductor 80 through conductors III, I38, contact I35, conductors I31 and I38, conductor I44, resistor I43, conductor I 42, contacts I28 and I24 and conductor I4I back to the conductor 5' and line conductor 80' previously described, thereby short-circuiting the coil I32 and preventing the energizing of this coil to release the cam- I30 and permit the shaft I2I to be returned to its normal position.

Assuming that one or more of the motors 26, 38,62 and 12 have been stopped, with the reset relay in the condition heretofore described, and that all of'these motors have subsequently been started in operation again with a resulting opening of all of the contacts I35, I35, I35 and I35",

, it is then necessary to energize the coil I32 to effect the resetting. of the relay I20 and this is brought about by a flow ofcurrent from the line contacts I28, and I25, conductor I41, coil I32, conductor I46, conductor I44, resistor M3, conductor I42, contacts I24 and I28, conductor I4I and conductor -I I5 back to line conductor 80 When the coil I32 is thus energized, the plunger i3| is elevated and the cam I30 and shaft i2I are permitted to return to the normal position shownin Fig. 4 under the influence'of the coil spring I38.

In order to prevent the starting of the motors I8, 26 or 34 or any-other motors connected to the buses 82 ,82 and 82 before all of the motors 26 38, 62 and 12 have been started in operation,

a circuit breaker I50 is connected in the line conductors 80, 80 and 80 at a point between the connections which are madeto the buses 8i, N

and 8 I and the connections which are made to the buses 62, 82 82. This circuit breaker I50 is similar in construction to the circuit breaker I00 and comprises a series of contact members I5I which are carried by a bar I52 and controlled by a coil I53; For the purpose of energizing the coil I53 of' the circuit breaker I50, connections are made with the line conductors including the connection from the conductor '80 through the conductor I54 which is connected with-the-previously described contacts I I0 which are controlled by the actuation of the circuit breaker I00. The other terminal of the contacts H0 is connected to a conductor I55 with the upper contact I21 in the reset relay. The lower contact I21 is connectedto a conductor I56with one terminal of the coil I53. The other terminal of the coil I53 is connected by a conductor I51 with a resistor I58 which is in turn connected through a conductor I58 with the line conductor 80. As a result of the connections just described, the coil I53 is connected in the closed circuit between the conductors 80"and 8|) at the timethat the reset relay I20 has been reset following the opening of-all of the contacts I35, I35, I35 and I35" and the starting of all of the motors 26, 33, 62 and 12 so that the circuit breaker I50 may then be operated to close the circuit leading to the buses conductor 80 through conductors II2, I38, I48,

82 82 and 82 with the result that when this 21 and the motor 34 for driving the exhauster fan '33 areconnected, asshowninFigJ'; 7 All of these which leads to -the conductor I62.

actuation of the contactors I6I of the adjacent motors are connected to the buses 82', 82 and 82 tomatically controlled by a coil I88 which is conin the same manner and a description of one set nected between two of the conductors I68 and of these devices will therefore sufiice for all of I68 leading to the motor I8, as shown in Fig. 2 them. For illustration, the motor 34 is connected As shown in Fig. 5, the damper 25 is mounted on through conductors I68, I68 and I68 with cona shaft I8I located in a section 24* of the conduit tact members I6I which are adapted to establish and this shaft is provided with an arm I82 carconnections with conductors I6 5162 and I62 ryin'g a weight I83 which tends normally to close which are in turn connected to t e buses 82", 82 the damper. After the damper has been manuand 62, respectively. The contactors I6I conally opened, it is adapted to be held in that open stitute parts of the motor starter I63 which is position by means of a cam I84 secured on the substantially similar to the motor starter 85 shaft I8I and having a notch I84 adapted to be previously described except that the connections engaged by a plunger I85 which serves as a latch are somewhat difierent, as will now be pointed member and which operates as the core of the out. The contactors I6I of the starter I63 are coil I88. When the coil I88 is energized, during operated by a rod I64 which has operating connections with a member located within and actuated by the coil I65, corresponding to the coil 88 previously described. The conductors I62 and I62 have connected therein overload coils I66 which correspond to the overload coils 88 of t construction previously described. These gidload coils I66 control contacts I61 correspo ding to the contacts 88. One terminal of each set of contacts I61 is connected through a conductor I66 with one of the terminals of the coil I65. The other terminal of one set of contacts I61 is connected by a conductor I 68 with the conductor I62 and the other terminal of one set of contacts I61 is connected by conductor I18 through a momentary push button contact "I to a conductor I12 circuit of the motor I8 and the stopping of the The conducmotor 34 also operates automatically to open the tor I18 is also connected through a normally circuit of the motor 26. closed push button switch I13 with a conductor In Fig. 6 of the drawings there is illustrated I14 which leads to the conductor I68 so that a another form of appa Drectieihg the circuit is maintained through the coil I65 after pre ent invention This r di e fly the contacts I6I have been closed, thus permitfro that us d in 1 in that 110 p ting the motor 84 to be maintained in operati n, heaters are used for heating the gases introduced The motor 26 for driving the mill 2'! is conint the arly sta s f th p s d n ttrolled in its operation by a starter I63 and the tempt is made to Convey the gases from the Waste motor I8 for driving the conveyor I8 i to the furnace for the purpose of destroying the trolled by a starter I63. These starters I63 and odors- AS in the 101111 of the invention Previously m are similar to the starter I63 except that described, t e s u m t r l 2 0. ta nin interlocking connections are provided so that the large P ge of water, s t uced to t starter I63 cannot be operated until the starter tank 0 a vacuum type filter having the form I68 has been actuated to start the motor 34 and Previously described- The solid material of the the starter m cannot be operated to start the Waste, nt n s m wat is r d m motor I8 until the starter I68 has been started the rotary drum of the filter y the Scraper to actuate the motor 28, F th purpose of and it drops into the hopper 212 into which a viding this interlocking ti there i portion'of dried sludge 213 is introduced by a belt stituted for the conductor I68 in each of the conveyor h mixture 01 Wet and dried mm and was a connection leading partially dried waste passes from the hopper into through co t t [15 h h are controlled by the the screw conveyor 215 which is driven by a motor 216. The screw conveyor discharges the material into the upper end of the drying tower 211 which is like that previously described, being provided adjacent its upper end with a pair of rotary chopping devices 218.which-are adapted to reduce the waste to a finely divided state before it drops by gravity through the tower. Hot gases of combustion are introduced into the tower 211 through a conduit 218 which may be controlled by a damper 288, as in the other form of the invention. These hot gases have a drying effect upon the finely divided sludge dropping through the tower and are themselves reduced in temperature before the'mixture reaches the rotary mill 28I which is like the mills previously described, being provided with a rotary shaft 28" driven by a .motor 282 and having mounted thereon in the maincasing the heaters 283 and also an impeller 284 located in the auxiliary casing.

the plunger I85 is held in its upper position as shown in Fig. 5, so that it engages the notch I84 and holds the damper in its open position. If he operation of the motor I8 is arrested and its circuit is automatically opened by the motor starter I63", as heretofore described, the coil I68 is deenergized with the result that the plunger I85 falls by gravity and permits the cam I88 and the shaft I8I to be turned by the weight I83 to close the damper and shut off the flow of hot gas to the tower 28. It will be apparent that the same result will be brought about by the stopping 01' either of the motors 26 and 34 inasmuch as the stopping of the motor 26 automatically opens the motor starter. For example, on the starter I63, the contacts I16 are connected by one conductor I16 with the contacts I61 of the starter I63- corresponding to the contact to which the conductor I68 is connected in the starter I63, and the other terminal of the contacts I15 is connected through a conductor I11 with the conductor "5i leading to the starter I63 so that it is necessary to actuate the starter I63 to close the circuit of the motor 34 and to close the contact I15 before the starter I63- can be actuated to establish a circuit through its coil I66. Similar connections are made from the starter I 63 to the contacts I15 oi the starter I63 so that the starter I 63* must be actuated to close the circuit of the motor 26 before the starter I63 may be actuated to close the circuit of the motor I8 and establish a circuit through the coil I86 of that starter.

In order to prevent the flow of hot gases into the drying tower 28 and the mill 21 in case any From the auxiliary casing of the rotary mill, one of the motors I8, 26 or 34 is shut down, the the gases steam and finely divided solid material closing of the damper 25 in the conduit 24 is 4111- are carried upwardly through a conduit 285 which the time that the circuit to the motor I8 is closed,

. conveys them to the rotary separating device 289.

The gases, vapors and the like are separated by the device 289 and pass'upwardly through a conduit 290 which communicates with the intake of a fan 29! driven by a motor 292." The fan discharges these gases and vapors through a conduit 293 which is connected to deliver. them as hereinafter described. The solid materials in the waste which are separated in the separating device 289,-are delivered downwardly through a conduit 294 which communicates with two branch conduits. One branch conduit 295 deposits a portion of the finely divided and partially dried waste onto the belt conveyor 214 which conveys it to thehopper 212 as previously described. The other branch conduit 293 discharges the remaining portion of the partially dried waste into a hopper 29'! by which it is delivered to a screw conveyor 298 driven by the -motor 299. The screw conveyor discharges the material into the upper end of a drying tower 300 which has located in the upper part thereof the rotary chopping devices 3M. The material then drops by gravity through the tower 300 and is mingled with hot air which is introduced through a conduit 302; this air being heated by the furnace in which the waste is burned, as hereinafter described. If it be found that the waste does not give suflicient heat for carrying on the process, coal or other fuel may be intermingled with the waste in the mill into which the waste passes from the tower and for this purpose a fuel hopper 303 is provided with its lower end communicating with the mill through a conduit 304 The materials'falling through the tower 300 are-delivered by gravity into the rotary mill 305 which is similar in construction to the mill 28! and the other mills previously described. The shaft 306 of this mill has mounted thereon the rotary heaters 30! and the impeller 308 and it is operated by an electric motor 309. The finely divided and dried materials are discharged upwardly through the impeller 309 and conduit 3l0 which communicates with a fan 3H driven by the motor 3l2. The fan 3 discharges the materials through the conduit 3l3'which has a burner 3 on the discharge end thereof within the chamber of the furnace 3l5. The dried material is burned in the furnace chamber as it is discharged through the conduit and the air for primary combustion is supplied by the conduit 302, previouslyreferred to. which communicates with the drying tower 300. The air passingto the conduit 302 is heated in the space 3l6 which lies between the double walls of the furnace, the conduit 302 being connected with this space at one side of the furnace while at the other side the furnace is provided with an opening 3",

3l8'which leads through the hollow division wall 3l9 ofthe furnace. Theash produced by .the

combustion of the materials in the furnace chamber drops through the opening 320 formed in the bottom wall .of the furnace which is constructed in the shape of an inverted cone. The

gases of combustion pass upwardly from the furnace chamber through a conduit 32I which communicates with a separating device 322 by which the ash is separated and discharged downwardly through an opening 323. The-gases pass upmotor 340.

wardly from the separator 322 witha portion thereof passing into the conduit 219 which communicates with the drying tower 211, as previously described. The remaining portion of the gases from the separator 322 pass upwardly to the stack 324 and are wasted to the atmosphere.

exhaust fans are not in operation and the introduction of hot gases into the first stage mill when the screw conveyor 215 is not feeding waste to that mill.

In Fig. 7 there is illustrated another form of the invention which differs from those previously described in that the first stage of the drying operation is effected by a drier of the perforated belt or screen type, in addition to which means are provided for effecting the drying either by hot air produced in the hollow wall of the furnace or by heated gases produced by a preh'eater. In this form, the sewage waste containing a large percent of water is introduced, as before, into the tank of a rotary vacuum filter 330 of the construction previously described. The solid material, including some ,Water, is scraped off of the rotary cylinder by the scraper 330, and is discharged .into a hopper 33! which feeds it onto one end of an endless perforated belt 332 constituting a part of the drier 332. A series of compartments 332 'are mounted beneath the upper stretch of the'belt and are adapted to discharge through the belt heated air or'gas which is supplied through a series of branch conduits 332 leading from a supply conduit 333. A hood 332 is mounted over the upper stretch of the perforated belt and is adapted to catch the heated air and gases which pass upwardly through the finely divided waste material moving over the belt, thus effecting a suband which discharges into a conduit 338 leading to the furnace or to one of the preheaters, as hereinafter described.

The hopper 334 discharges into a variable speed screw conveyor 339 which is driven by a Y The materials are discharged by the screw conveyor into the upper end of a drying tower '34! which is similar to those previously described and which is provided in the upper part thereof with the rotary power driven cutters 342 adapted to efiect a further subdivision of the waste material as it passes between them. The drying tower 3 is adapted to receive heated air through a conduit 343 leading from the hollow wall of the furnace and it may also receive heated gases through another conduit 343 fed by one of the preheaters hereinafter described. These two conduits 343 and 344 may have dampers 345 and 346 connected therein, respectively, for shutting off the flow. through either one when desired. The finely divided waste material drops through the tower 34! into the roconduit 355 to the interior of the furnace 356 where it is burned continuously as it is discharged from the mouth of the conduit through a suitable burner. The air for primary combustion is supplied through the conduit 343 leading to the tower 3 and if the waste is not of sufflcient heating value to supply the necessary heat for carrying on the various steps of the process, coal or other fuel may be added through a hopper 351 which is mounted above the mill 348 and arranged to communicate with the mill through a conduit 358.

The furnace 356 has a hollow wall construction providing an inner space 356 into which air is .drawn through an opening 353. This inner heating space is connected with the conduit 343 previously described so that a quantity of air is con tinuously heated during the operation of the furnace and supplied to the drying tower 3. As the waste burns in the furnace, the ash is dropped through the opening 363 in the tapered bottom wall of the furnace and the gases of combustion pass upwardly through a conduit 36! which leads into the casing of a preheater 362. The casing of the preheater 362 is connected by a conduit 363 with a second preheater 364 from which the gases of combustion; are passed through-a conduit 365 by a fan 365 to a separator 366 by which the finely divided ash is separated and dropped downwardly through a conduit 366 while the gases pass upwardly through an outlet 366. The first preheater 362 includes a coil 361 which is connected at its lower end with a fan 368 driven by a motor 363 and'adapted to draw in air from the atmosphere through a conduit 313. This air is circulated through a coil 361 of the preheater and is then discharged into the previously described conduit 333 by which heated air is supplied to the drier 332. This conduit 333 may be connected by a conduit 31 I with the previously described conduit 343 by which heated air is supplied to the tower 3 and a damper 312 may be located in this interconnecting conduit so that, when desired, the preheater may be employed for supplying heated air both to the drier 332 and the tower 3. If the preheater 362 is not in operation, heated air may be supplied through the conduit 343 to the drying tower 341 and also to I the perforated belt drier 332.

The conduit 338 which conveys heated air, gases and vapors from the hood of the drier 332 communicates with the furnace chamber through the hollow division wall 356, thus supplying addiional air for combustion, and at the same time destroying the obnoxious character of the vapors which are drawn off in the drier 332. The conduit338 is connected by a branch conduit 314 with the coil 315 of the second preheater 364 and a portion of the hot air, vapors and gases is thus heated by the preheater and is then discharged into the previously described conduit 344 which leads to the drying tower 3. The conduit 344 communicates with a conduit 315 having a branch 313 leading from the conduit 333 and the lower end of this conduit 316 communicates with the furnace chamber, thus supplying additional air for combustion. The drier 332 is adapted to be driven by an electric motor which may be connected along with the other motors of the system in an electric circuit such as that illustrated in Figs. 2 and 2 so that there is an interlocking control of the actuation of all of the motors to prevent damage to any parts of the apparatus when other parts of the apparatus are accidentally shut down.

In Fig. 8 of the drawings, there is illustrated another form of the invention. In this form, the waste containing a large percentage of water is introduced into the rotary vacuum filter 383 which is similar to those previously described and from which the wet waste material is removed by a scraper 383 and discharged into a hopper 38l. The hopper discharges the material onto the perforated belt 382 of a drier 382 which has a series of compartments 382 located beneath the upper stretch of the belt and adapted to discharge through the belt a quantity of heated air which is received by the compartments through branch conduits 382 leading from a supply conduit 383 adapted to receive heated air from a preheaterheated by the gases of combustion, as hereinafter described. The drier 382 is provided with a hood 382' which collects the air and vapors passing upwardly from the waste on the belt 332' and discharges it through a conduit 385-connected with a fan 386 which is driven by a motor 381 and which discharges the hot air and vapors into a conduit 388 adapted to convey the vapors either to the furnace or to a preheater, as hereinafter described. The waste which is partially dried in passing over the compartments 382 on the perporated belt is discharged into a hopper 383 through which it falls by gravity into a rotary screw conveyor 333 driven by the motor 331. The screw conveyor discharges the materials into a drying tower 332 which has powerdriven rotary chopping devices 333 located in the upper part thereof. Hot air and vapors adapted to effect a further drying of the waste are introduced into the tower 332 through a conduit 334 and additional fuel for combustion may be supplied and mixed with the waste in the wall below the tower by means of a hopper 335 and a connecting conduit 336.

\ The finely divided material falling through the tower 332 is discharged into the rotary drying mill 331 which is similar in construction to those previously described, being provided with a shaft 338 which is driven by a motor 333 and which has mounted thereon the rotary beating devices 433 and the; impeller 43I. The impeller 43l discharges the waste material, hot air, vapors and the like upwardly through a conduit 433 which is connected with a fan 434 driven by a motor .435. The fan 434 is rotated to discharge the materials from a conduit 436 into the combustion chamber of a furnace 431 where the materials are burned as they are supplied the air for primary combustion being furnished to the tower 332 by the conduit 334 heretofore referred to. Additional air for combustion, along with the objectionable gases from the drying apparatus 382. is supplied to the furnace 431 through the previously mentioned conduit 388 which extends through the top wall of the furnace. The ash resultingfrom the combustion in the furnace chamber drops through the opening 438 at the bottom and the gaseous products pass upwardly .through a conduit 433 which leads to a separator 7 a which may be carried in conduit 4" to a preheater 4l2.

conduit 383, which has previously been described I as supplying heated air to the pans 362 which are located beneath the perforated belt of the wardly through another conduit 6 to a second dryer 562. The hot passing through the gases of combustion, after preheater 2, continue uppreheater 4" in which there is locateda heating coil 8. This coil is connected by a conduit 9 with the conduit 386 so that a portion of the hot air and gases passing off from the dryer 362 may be passed through the preheater 4H and heated to a further extent before being supplied from the coil 6 through the conduit 394 to the drying tower 362. The gases of combustion pass upwardly from the preheater 4|! through ,a conduit 420 which is connected to the intake ofa fan 42l drivenby a motor 422 and adapted to discharge the gases through a stack 423 to the atmosphere. The furnace shown with this form of the invention embodies means for generating steam, consisting of a number of water tubes 424 which are located within the refractory walls of the furnace and connected with headers 425 and a steam drum 426 in which the generated steam may be collected and then drawn off through a pipe 421. In this form of the invention, as in those previously described, the various motors for operating the drying apparatus, the preheaters and the exhaust fans may be connected in an electrical system so that their operations are automatically controlled in the manner heretofore described.

In Figs. 9 and 10 of the drawings, there is illustrated another modification of the invention in which the preliminary drying operation is effected by a rotary kiln and in which the heat generated by the combustion of the waste products is utilized somewhat difierently from its utilization in the embodiments of the invention previousiy described. In this form, the waste material containing a large percentage of water, is introduced into the tank of a rotary vacuum type separator 466 comprising the usual drum 436- and a scraper 466 by which the solid material, con- Y taining some water,'is removed from the screen of the drum and deposited in a hopper'nl through which it falls into the rotary screw conveyor 462 which is driven by a motor 433. The screw conveyor feeds the material into the upper endof a drying tower 434, similar to those previously described, which is provided in its upper with rotary power driven chopping devices 4 36by which the material is reducetl'to a finely divided state. Heated air for drying purposes is introduced into the upper part of the tower through a condut 466 and the finely'divided material falls throu h this heated air to the bottom of the tower where it is received by a rotary screw conveyor 431 driven by amotor 436. The

screw conveyor 431 feeds the materlals into a rotary drying kiln 446 which comprises a cylindrical steel shell 44.! arranged to'revolve around its longitudnalaxls which is inclined downwardly from the inlet end. his shell is provided on its interior with longitudinal blades-or-vanes 446 which nickupmaterlalduringthe rotation of the of a fan 4" driven subjected to a thorough mixing with the current of hot air which passes through the shell during its rotation, the hot air being supplied from a tower 434 and the conduit 436. The shell is closed at its upper .end by a stationary head or casing 440 and at its lower end it discharges into a tower or casing 44! in which the solid materials'settle to the bottom and are collected by a rotary screw conveyor 442 which is driven by a motor 443. The upper end of the tower casing 44! communicates with a conduit 444 through which the veying the hot gases to the furnace where the objectionable odors are destroyed.

The solid material which is discharged by the rotary drying kiln is fed by the screw conveyor into the upper end of a drying tower 450 into whichhot air may be introduced by a conduit 4 5l leading from the conduit 436 previously described. If desired, hot gases and vapors may also be introduced through a conduit 452 having a connection with the conduit 449, as hereinafter re ferred to. Power driven rotary chopping devices 453 are mounted in the upper part of the tower for effecting a further subdivision of the material before it drops-downwardly through the hot air and gases in the tower. If desired, coal or other fuel may be introduced into the tower from a hopper 454 in order to provide additional heat for maintaining the system when the solidmaterial is subsequently burned. From the tower 456, the solid material passes along with the hot air and gases and intermixed fuel into a rotary pulverizer and dryer 455 having the construction previously described, including a shaft 456 driven a motor 451 and having mounted thereon the rotary beating devices 456 and the impeller 459. The impeller discharges the finely divided material along with the hot air, vapors and gases upwardly thetower 456 through the conduits 451 and 452 and additional air for combustion may/"be supplied through a. branch conduit 466 which leads directly to the lower part of the furnace chamber from the conduit 452. Additional air may be supplied from a; conduit 461 ;which leads downwardly through the hollow division wall 465* of the furnace and which supplies the hot air and gases to the conduit 452 and 466. The conduit 461 is connected with the coil 466 of a preheater 466'and the other end'of this coil is connected with the conduit 44! which has previously been described as receiving the hot air and gases from therotary drying kiln 446. The furnace is provided with a hollow. wall-465" having an inner space 466' into which airis drawn from the atmosphere through ports 465 This'air is heated from the furnace chamber and passes upwardly through a conduit 4'" which leads to the intake by a motor 4l2. The fan discharges the hot air upwardly to the coil 413 of a preheater 414. The coil 413 is connected to the previously described conduit 436 by which the heated air is discharged into the tower 434. The hot gases of combustion are discharged from the furnace chamber through a conduit 415 which leads to a separator 416. In this separator, the finely divided material which may be carried by the gases is separated and discharged downwardly through a conduit 411, while the hot gases pass upwardly through'a conduit418 and into the preheater 414 where they serve to add additional heat to the hot air which passes through the coil 413. From the preheater 414, the hot gases of combustion pass upwardly through a conduit 419 to the previously described preheater 469 by which the hot gases and vapors received through the conduit 449 are heated. From the preheater 469, the conduit 480 to a separator 48L In this separator, any ash and the like which may remain in the hot gases .is separated and discharged through an opening 48! while the gases pass upwardly through a conduit 4|! and are discharged to the atmosphere through a stack or the like. The ash which passes downwardly from the separator 416, adjacent the furnace, may be mixed with ash passing downwardly from the furnace through a conduit 483 and all of this ash may be continuously drawn off through suction devices or the like. As in the forms of the invention previously described, the various electric motors for operating different parts of the apparatus may be connected in an interlocking electrical system so that the apparatus may be operated and controlled as heretofore described to prevent injury to any parts of the apparatus and to maintain the proper operation of all of the parts regardless of the rate at which the sludge material is fed to the apparatus.

In addition to the foregoing embodiments of the invention, we have described and claimed in our copending divisional application, Ser. No. 170,465, filed October 22, 1937, another form of apparatus embodying the present invention and particularly adapted for use in disposing of garbage or a mixture of garbage and other waste materials, wherein means are provided for cleaning the gases and vapors before venting them to the atmosphere, and in our copending divisional application, Ser. No. 170,464, filed October 22, 1937, there is described and claimed still another form of the invention wherein the drying step of the process is carried on in a single mill constructed in the form of a rotary drum or kiln.

The various forms of apparatus herein described may be employed for disposing of sewage waste, garbage and other forms of waste, either separately or as mixtures of different forms of waste, and it is intended that the appended claims be so construed and that the term sewage waste and the like? as used in the claims he interpreted to include any waste or mixture of wastes or other material or materials of high moisture content capable of treatment by the process and apparatus of the present invention. Where reference is made in the claims tolthe burning of the from the waste material, it.is, of course, only the combustible gases which are burned, the remain ing non-combustible gases jected to a heat treatment to deprive them of their obnoxious character. ,Also, where reference is made to the separation of the solid material of the waste from the residue, it is to beundergases pass upwardly through agases given off by or separated being merely 'sub-' I waste material stood that the solid material is ordinarily wet when separated so that drying is desirable before the burning stage of the process is reached.

Although several forms of the improved apparatus of the present invention have been shown and described by way of illustration, it will be understood that the apparatus may be embodied in various other forms and that the improved method may be practiced in various ways coming within the scope of the appended claims.

We claim:

1. The method of treating sewage waste and the like, which consists in drying and comminuting the solid waste material, separating the comminuted solid material from the gases given off therefrom, effecting a further drying and a further comminution of said material, then burning said material and the combustible gases; and heat treating the non-combustible gases.

2. The method of treating sewage waste and the like, which consists in drying and comminuting the solid waste materiaL'separating the comminuted solid material from the gases given off therefrom, effecting a further drying and a further comminution of said material, then burning said material and the combustible gases and heat treating the non-combustible gases, and utilizing the heat of combustion for drying a further quantity of the solid waste material.

3. The method of treating sewage waste and the like, which consists in comminuting the solid waste material, effecting the comminution and drying of said material in multiple stages, burning the comminuted and dried material from the last of said stages, and utilizing the heat of combustion for drying said material in each of said stages.

4. The method of treating sewage waste and the like, which consists in separating the solid waste material from the liquid, comminuting and drying said separated material in a series of stages, supplying dried material from one of said stages and mixing it with the wetter solid material in advance of the first one of said stages, and incinerating the comminuted and dried material received from the last of said stages.

5. The method of treating sewage waste and the like, which consists in separating the solid waste material from the liquid, comminuting and drying said separated material in a series of stages, supplying dried material from a later one of said stages and mixing it with the wetter solid material in an earlier one of said stages, incinerating the comminuted and dried material received from the last of said stages, and utilizing the heat of combustion for effecting the drying of said material in each of said stages.

6. The method of treating sewage waste and the like, which consists in separating the solid waste material from the liquid, effecting the comminution and drying of said separated material in a series of stages, separating the comminuted material from the gases given off therefrom after it has passed through the first of said stage. and conveying the separated solid material to th next of said stages, and burning and heat treat 'ing said separated gases and the comminuted an dried material received from the last of sai stages in a closed space.

7.'The method of treating sewage waste an the like, which consists in separating the $011 from the liquid residue, effectin the comminution and drying of said separate material in a series of stages, separating the com minuted material from the gases given off there terial to the next of 5 drying purposes.

from after it has passed-through the first of said stages and conveying the separated solid me.-

said stages, incine'rating the dried and comminuted material received from the last of said stages, and utilizing the heat of combustion for heating a quantity of said separated gases supplied for drying said material in one of said stages. a

' 8. The method of treating sewage waste and the like, which consists in separating the solid waste material from the liquid residue, effecting the comminuti'on and drying of said separated material in a series of stages, separating the comminutedmaterial from the gases given ofi therefrom after it has passed through the first of said stages and conveying the separated solid material to the next of said stages, incineratingthe dried and comminuted material received from the last of said stages, utilizing the heat of combustion for heating a quantity of said separated gases supplied for drying said material in one of said stages, burning saidseparated gases, and.

utilizing the heat produced by the combustion of said material and said gases forheating a quantity of air supplied to 9. The method of disposing of sewage waste and the like, which consists in continuously feeding the solid waste material to a drier, causing a' flow ofr hot gas to saidmaterial in said drier, comminuting said material while it is being dried in said drier, and regulatingthe flow of said hot gas in proportion to the supply of said waste material to said drier.

10. The combination in apparatus for disposing of sewage waste andthe like, of means for separating the solid material from the liquid in the waste, means including a mill for pulverizing and drying said solid material, a furnace for burning said material, and means for conveying said material from said mill to said furnace.

11. The combination in ing of sewage waste and the like, of means for separating the solid material from the liquid in the waste, a drying tower through which said material passes, a mill for pulverizing and drying said material received from said tower, a furnace ior incinerating said material, and means for conveying said pulverized and dried material to said furnace.

12. The combination in apparatus for disposing of sewage waste and'the like, of means for separating the solid material from the liquid in the waste, a drying tower through which said material passes, a mill for pulverizing and drying said material received from said tower, a furnace for incinerating said-material, means for conveying said pulverized and dried material to said furnace, means for utilizing the heat generated in said furnace for heating 'air and supplying it to said drying tower, and means for automatically controlling the flow of said hot air to said drying tower.

13. The combination in apparatus for disposing of sewage waste andthe like, of'means'ior separating the solid material in said-waste from the liquid, drying means, means for conveying said material from said separating means to said drying means, means-for pulverizing said material in said drying means, a furnace, andmeans for conveying said pulverized and dried material to said furnace.

14. The combination in apparatus for disposing of sewage waste and the like, or means for the first of said stages for apparatus for disposseparating the solid material in the waste from the liquid, a drying tower adapted to receive said solid material from said separating means, means for comminuting said material in' said drying tower, a mill adapted to'receive said material from said drying tower, and a furnace adapted to receive and burn the solid material discharged from said mill.

15. The combination in apparatus for disposing of sewage waste and the like, of means for separating the solid material in the waste from the liquid residue, drying means, means for conveying said solid material to said drying means, means for mixing dried waste material with the wet waste material conveyed to said drying means, means for mixing and comminuting said wet and dried waste material in said drying means, means for pulverizing and eflecting a further drying of said waste material, means for separating the gases from the pulverized solid material, a furnace, and means for conveying said separated solid material to said furnace.

16. The combination in apparatus for disposing of sewage waste and the like, of means for separating the solid material in the waste from the liquid residue, drying means, means for conveying said solid material to said drying means, means for mixing dried waste material with the wet waste material conveyed to said drying means, means for mixing and comminuting said wet and dried waste material in said drying means, means for pulverizing and efiecting .a further drying of said waste material, means for separating the gases from the pulverized solid'material, a furnace, means for conveying said separated solid material to said furnace, and means for conveying said separated gases to said furnace.

17. The combination in apparatus for disposing of sewage waste and the like, of means for Separating the solid material in the waste from the liquid residue, drying means, means for conveying said solid material to said drying means, means for mixing dried waste material with the wet waste material conveyed to said dryingv means,

means for mixing and comminuting said wet and dried waste material in said drying means, means for pulverizing and eifecting a further drying of said waste material, means for separating the gases from the pulverized solid material, a furnace, means for conveying said separated solid material to said furnace, and means for utilizing the heat generated in said furnace for heating air and conveying it to said drying means.

18. The combination in apparatus for disposing of sewage waste and the like, of means for separating the 'solid material in the waste from the liquid residue, drying means, means for conveying said solid material to said drying means, means for mixing dried waste material with the wet waste material conveyed to said drying means,

means for mixing and comminuting said wet and dried waste material in said drying means, means for pulverizing and eflecting a further drying'of said waste material, means for separating the gases from the pulverized solid material, a furnace, means for conveying said separated solid material to said furnace, and means for utilizing the heat generated in said furnace for heating said separated gases.

19. The combination in apparatus for disposing of sewage waste and the like, of a series of pulverizing and drying mills, means for partially drying wet sewage waste and conveying it to the first mill of said series, means located between from said tower,

the first and the last mill of said series for separating the gases from the solid waste material and causing the solid waste material to be conveyed to the next mill of the series, a furnace, and means for conveying the pulverized and dried solid material from the last mill of said series to said furnace.

20. The combination in apparatus for disposing of sewage waste and the like, of a series of pulverizing and drying mills, means for partially drying wet sewage waste and conveying it to the first mill of said series, means located between the first and the last mill of said series for separating the gases from the solid waste material and causing the solid waste material to be conveyed to the next mill of the series, a furnace, means for conveying the pulverized and dried solid material from the last mill of said series to said furnace, means for utilizing the heat genfurnace, means for utilizing the heat generated in said furnace for heating said separated gases, and means for conveying said heated gases to said second named mill and to said furnace.

25. The combination in apparatus for disposing of sewage waste and the like, of a drying tower, means for conveying wet tower, means for comminuting said material in said tower, a pulverizing and drying mill adapted to receive said material from said tower, means for exhausting the contents of said mill, a second pulverizing and drying mill, means for separating the gases from the pulverized and dried material exhausted from said first named mill, means for conveying said separated solid material to said second named mill, a furnace for burning said material, means for exhausting the contents of said last named mill and conveying it to said furnace, and means for conveying said separated erated in said furnace by the combustion of aid gases to the combustion chamber of said furnace.

solid material in said furnace for heatingflaid separated gases, and means for conveyi g said heated gases to one of the mills of said s ries.

21. The combination in apparatus for disposing of sewage waste and the like, of a drying tower, means for conveying wet waste material to said tower, means for comminuting said material in the upper end of said tower, means for heating said material in said tower, a pulverizing and drying mill adapted to receive said material from said tower, a furnace, and means including an exhaust fan for withdrawing pulverized and dried material from said mill and conveying it to said furnace.

22. The combination in apparatus for disposing of sewage waste and the like, of a drying tower, means for conveying wet waste material I to said tower, at hot air conduit leading to said tower, a mill adapted to receive said material a furnace, means for conveying saidmaterial from said mill to said furnace, and means for utilizing the heatgenerated by the burning of said material in said furnace for heatins air and conveying it to said hot air conduit.

23. The combination in apparatus for disposing of sewage waste and the like, of a drying tower, means for conveying wet waste material to said tower, means for comminuting said material in said tower, a pulverizing and drying mill adapted to receive said material from said tower, means for exhausting the contents of said mill, a second pulverizing and drying mill, means for separating the gases from the pulverized and dried material exhausted from said first namedmill, means for conveying said separated solid material to said second named mill, a furnace for burning said material, means for exhausting the contents of said last named mill and conveying it 'to said furnace, and means for utilizing the heat generated in said furnace for heating said separated gases.

j 24. The combination in apparatus for disposing of sewage waste and the like of a drying tower, means for conveying wet waste material to said tower, means for comminuting said material in said tower, a pulverizing and drying mill adapted to receive said material from said tower, means for exhausting the contents of said mill, a second pulverizing and drying mill, means for separating the gases from the pulverized and dried material exhausted from said first named mill, means for conveying said separated solid material to said second named mill, afurnace for burning said material, means for exhausting the contents of said last named mill and conveying it to said 26. The combination in apparatus for disposing of sewage waste and the like, of a pulverizing and drying mill, means for conveying the solid waste material to said mill, a second pulverizing and drying mill, means for exhausting the contents of said first named mill, means for separating the solid ingredients of said contents from the gases therein and conveying said solid ingredients to said second named mill, a furnace, and means for exhausting the contents of said second named mill and conveying them to said furnace to be burned.

27. The combination in apparatus for disposing of sewage waste and the like, of a pulverizing and drying mill, means for conveying the solid waste material to said mill, at second pulverizing and drying mill, means for exhausting the contents of said first named mill, means for separating the solid ingredients of said contents from the gases therein and conveying said solid ingredients to said second named mill, a furnace, means for exhausting the contents of said second named' mill and conveying them to said furnace to be drying mill, means for exhausting the contents of said first named mill, means for separating the solid ingredients of said contents from the gases therein and conveying said solid ingredients to said second named mill, a furnace, means for exhausting the contents of said second named mill and conveying them to said furnace to be burned, means for utilizing a part of the heat generated in said furnace for heating said separated gases, and means for conveying a part of said heated gases to the combustion chamber of said furnace and for conveying the remainder of said heated gases to said last named mill.

29. The combination in apparatus for disposing of sewage waste and'the like, of a pulverizing and drying mill, means for conveying the solid waste material to said mill, a second pulverizing and drying mill, means for exahusting the contents of said first named mill, means for separating the solid ingredients of said contents from the gases therein. and conveying said solid ingredients to said second named mill, a furnace, means for exhausting the contents of said second named mill and conveying them'to said furnace to be burned,

- and means for supplying additional fuel to said second named. mill.

waste material to said 

